Automatic telephone system



April 30, 1929. M. L. NELSON AUTOMATIC TELEPHONE SYSTEM Original Filed June 12, 1924 ll Sheets-Sheet 1 Q59 & Eimw Mus KEGQM April 30, 1 929.

M. L. NELSON I 4 AUTOMATIC TELEPHONE SYSTEM Original Filed June 12. 1924' 11 Sheets-Shut 2 i April 30, 1929. M. LQNELSON 1,?1.'1,-20:=s.

AUTOMATIC TELEPHONE SYSTEM Original Filed June 12, 1924 ll Sheets-Sheet 4 HMMIhM Mimi April 30, 1929. M. N ELSON 4 1.711205 AUTOMATIC TELEPHONE sYs'rm'A OriginalFiled June 12, 1924 11 SheQts SheeVG A (so/ma) April ,:1929. M. 1.. NELSON ,711 2 5 AUTOMATIC TELEPHONE SYSTEM I Original Filed Jilne 12, 1924 11 Sheets-Shee't v April 30; 1929.

M. L. NELSON AUTOMATIC TELEPHONE SYSTE M Original Fild June 12, 1924 11 sheets-sheet s Mkk mural-1701 R E-72H L- NEZslJn TSK wk? 9. 5 hk i WMN QM 1b.. g I. g 1 1 Sm \Q I Em 1N. m JD Hu 8% Squall! \Rww N 1 n m m EN M N MW hywN E i F5 April 30, 1929. M. L. NELSON 20 AUTOMATIC TELEPHONE SYSTEM Original Filed June 12, 1924 11 Sheets-She 9 M. L. NELSON AUTOMATIC TELEPHONE SYSTEM April 30, 1929.

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' April 30, 1929. M. L. NELSON' 1,711,205

AUTOMATIC TELEPHONE SYSTEM Original Filed June 12, 1924 ll Sheets-Sheet 11 FIEWE'Z L. NEZsc/n Patented Apr. 30, 1 929.

; UNIT-ED STA MARTIN L. NELSON, or PAR-K RIDGE, rumors, .Assrcnon, BY iunsnn ASSIGNMENTS,

To AUTOMATIC ELscTn-rc Inc, or CHICAGO, ILLINOIS, A CORPORATION or DELA- WARE.

AUTOMATIC TELEPHONE SYSTEM.

Application filed June 12, 1924, Serial No. 719,459. Renewed March 7, 1928.

ably amongstthemselves as to the number of digits they contain.

One object is the provision ofsimple and eflicient arrangements in a director for causing the director tobe cut off at the termination of the transmission oi the last digit res gardless of the number of digits contained in the registered number;

Another objectis the production of new and" improved circuit arrangements whereby all code digits which'are normally transmitted in accordancewiththe setting of the oifice register are cancelled at-the end of the ofiice registration, and the sending mechanism is prevented from starting until a subscriber digit is registered.

It is a further object to provide a new'and' improved vibrating interrupter for generatiu them'ipulses tran smitted by the sender.

There are several other objects and tea tures ofthe invention which can be under-;

stood best from a perusal of the detailed description which is to follow. V

lteterring now to the drawings, Fig; 1 is a map showing the relative positions and the relative sizes of the variousjotfices o f the exchange; Figs. 2 and 3 show-a trunking dia: gram which is'sufliciently complete to enable the entire inter-office trunkingnet-work, as well as the trunking local to each office, to be understood; Figs. 410, inclusive, are circuit drawings showing all the apparatus involved in a call from subscriberin Meadow at one end of the net-work to a subscriber in Irving at the other end of the net-work (see Fig.1) and Figs. 11-13, nclusive, are mechanical drawings [of the improved vibrating inter rupter used in connection with the sending equipment of the director.

,Reterringnow particularly to Fig. 1, the Edgewater, Pont1ac Centre, Main and Mar ketoiiices are all main offices in a direct trunk net-work of the usual multi-oflice type. The

' Irving and Augusta.

Cedar and Meadow offices, on the other hand,

.may be considered as satellites of the Edgewater oflice, and in the same way the Irving and Augusta ofiices may be considered as satellites of the Main ofiice. All of the offices shown are automatic oflices except'Ii-ving and Augusta which are manual ofiices. I

The inter-office trunking between the various main offices of the system, of course, presents no difficulty, and'no directors are used in the main offices. Consequently, the only place where directors are used is in the'satellite ofiice's Cedar and Meadow, and they are usedthere in order to permit the so-called Universal numbering system, that is, a system-in which any-one subscribersnumber. remains the same regardless otfrom which v station it is called. Also, the directors do not enter into the consideration of calls coming in toiCedar and Meadow by way 0:? Edgewater, and it is only on calls actually originated in Cedaror Meadow that directors are used, as will be pointed out hereinafter.

Referring now particularly to the trunk ing diagram shown in Figs. 2 and 3, this diagram showsthe trunking in the main ofiices Edgewater and Main and in the satellite officeslvieado'w and Cedar, and shows how calls are completed from main to the manual office's Considering first the office Edgewater, a calling line, iorexauiple the line of substation A is connectcdby the associated line switch L8 to an idle first se- 1l-@1-,for example the first selector In case the first digit dialled by the calling subscriberis the digit3,tl'1e first selector cxtends a connection to a local thousands selector, such as the selector if, and the second or 9, anoutgoin'g trunk is seized and a connectlon is extended by way of a repeater,

such forexample as one of the repeaters E K, inclusive, toan incoming selector in Meadow, su'ch as one ofthe incoming selectors S S inclusive. The next digit dialled picks a local connector in Meadow, and the next two digits extend the connection to the called line.

When a call is extended from Edgewater to Main by way of, for example, the repeater It it comes in at Main on the incoming selector S and, upon the dialling of the next digit, a local thousands selector, such the selector S is seized in case the second digit is 9 or under, but if the second digit is O a special selector, such as S is seized and the call is extended to one of the manual otlices Irving or Augusta by way of a repeater, such as R or R Considering now calls originated in Main, when the first selector 8 is seized the call is extended to a local thousands selector, such as S, if the first digit dialled is 6, and is thereafter extended to a local line or to a line in Irving or Augusta, depending upon whether the second digit is O or some other digit. On the other hand, if the first digit dialled is 3, 4;, 5 or 7 the connection is extended by way of a repeater, such as the repeaters R 11, inclusive, to one of the other main offices, and if the digit is 3 the call may be extended by way of the repeater R t the incoming thousanos selector S. in the Edgewater otiice and is thereafter com pleted locally or is trunlted to Cedar if the next digitdialled is 0.

Considering now calls originated in Meadow, when the line of substation A is calling the line switch LS selects an idle selector such as S and the director selector DS associated with the trunk circuit TC selects an idle director. In case the first digit dialled is 3, the second digit is O and the third digit is (3, 7, 8 or 9, the director does not transu'iit 7 digit in response to the reception of the digits 3 and 0, but tii'ansn'iits the third it received the first digit of the numher and the selector S selects a local selector, such as the selector S, S S or S and the call is extended to a local line in Meadow. On the other hand, the third digit is orunder, instead of the digits named, the connection is extended by way of a repeater, such as the repeaters IP11, inchiisive, to one of the incoming selectors S -S inclusive, in the nearby satellite otlice Cedar and is there conu ileted locally by way of one of the selectors named. On the other hand, as will be pointed out more in detail hereinafter, if the first two digits received by the director are not 3 and 0 but are digits which indicate that the desired line terminates in one of the main otlices or in one of the i'nanual offices of the sy. cm, the director automatically transmits the code digits 3 and 0, followed by the reg istcred number of the called line. Responsive to the transmission of the code digit 3 by the director, the selector S extends the connection by way of a repeater in the third group such as the repeater R to an incoming selector S in Cedar, which responds to the second code digit 0 and extends the connection by way of a repeater such as R to the incoming otfice selector S in Edgewater. From this point the connection is completed just as though the calling subscriber were a local subscriber. in Edgewater.

Considering now calls originating in Cedar, when the subscriber at substation at A" is calling the line switch LS extends the connection to an idle selector such as the selector S. and the director selector DS associated with the trunk circuit TC selects an idle director. In case the first two digits dialled are 3 and 0 the director does the same as the director in Meadow, omitting the first digits and re-transmitting the remaining digits to complete the connection in one of the satellite o'tlices Meadow and Cedar.

In case the first two digits indicate that the calling line is reached by way of one of the main ofiices of the system, the director transmits the code digit 0 and then repeats the registered number. lhe transmission of the code digit 0 results in the connection being extended by way of a repeater such as the repeater R to the incoming selector S in Edgewater, from which point the connection is extended just as though the calling subscriber were a local subscriber in Edgewater. I

Considering now the circuit drawings com prising Figs. l10, inclusive, Figs. 4, 5 and (3 show the trunking equipment necessary to extend a connection from the subscriber at substation A in Meadow to the subscriber at substation A in Irving. This connection, when established, includes the line switch LS, the trunk circuit TO, the selector S, and the repeater R in Meadow; the selector S and the repeater R in Cedar; the selector S and the repeater R in Edgewater; the selectors S and S and the repeater R in M i g and the cord circuit CC and the jack J in Irving. I i

It will be noted that the circuits of the selectors S S and S, Fig. 5, are not shown. The circuits of these selectors, it' may be pointed out, nay be sin'iilar to the circuit of the selector S, Fig. l. it will be'noted that the circuits of the repeaters R and R Fig. 5, and the repeater B, Fig. 6, are not shown. The circuits of these repeaters may be the same as the circuit of the repeater R, Fig. 5.

It is thought that nothing further need be said about the trunking arrangen'ient at this point,and it will suilice to point out that the line switch LS is, mechanically, of the well known rotary type, and that its wipers havev no normal position but-are moved in a forward direction only and are advanced upon the back stroke of the associated stepping n'iagnet rather than upon the front stroke. The director selector DS is a non-niunerical trunk hunting switch and, from a mechanical standpoint, 15 similar to the l ne switch LS. The selector S is a standard two-wire selector.

from a circuit standpoint, and mechanically, is of the well known vertical and rotary type and its bank contacts are ar anged in horizontal rows or levels.

Referring now to the director shown in Figs. 7-10, inclusive, this director comprises essentially an office register OR which is a vertical and rotary switch of the usual type and which registers the first two digits of a number, together with the so-called digit registers Dlit lfit inclusive, Fig. 10, and the sender. 8. The sequence switch S, Fig. 7, distributes the various impulses in the called number amongst the various registers. The first twoseries of impulses are transmitted to the vertical and rotary magnets, respectively, of the office register OR,

Fig. 9, and the remaining series are distribut- (Xi to the various nigit registers DR DR, inclusive, Fig. 10.

Although only one set of bank contacts is shown associated with the mice register QR it will be understood that there are one hundred such sets of bank contacts and that each set of bank contacts is connected to the right hand side of the intermediate distributing, {frame TDF in the same manner as, thc'set shown.

The function of the sequence switch S, Fig. 7 isprimarily to associate the-sender first with the oflice register OR-until the ofiice code is transmitted, and then with the various digit registers shown in Fig. in order until the subscriber digits of the numb-er are sent out after which the sequence switch isagain advanced toca-use the trunk circuit TC, Fig. i, to switch through and the director to be freed. r

Referring now particularly to Figs. 11, 12 and 13, those dr u ngsshow three views of the new and improved vibrating interrupter. Fig. 11 is a front view or" the interrupter; Fi 12 is a view from the right side; and Fig. is a rear view. This interrupter comprises, essentially, the magnetcoil 2 and the reed 5 which excited by the magnet coil 2 and controlled in its period of vibration by the weight 6.

The core of the coil. 2 is provided with the soft iron poles 3 and i, which,together with the spring steel reed 5, form the return magnetic circuit. The small strip of brass is secured to the end of the 113018-P1QCQ 4 in order to prevent the reed 5 from coming close enough to the pole piece 4 to stick. The reed 5 carries a contact w iich engages with a similar contact on'the spring 7 when the reed 5 is attracted toward. the core. These contacts areused for short circuiting the winding '2 when the reed 5 is attracted soas'to cause the winding to deenergizeand permit the reed to swing away again. The point at-which the v short circuiting contacts close may be adjusted by the screw 12 which is provided witha lock-nut 13 to hold it inits adjusted position. The insulated tip of the screw 12 bears against the spring 7. V The interrupter springs 8 and 9 are ,provided with contacts which are normally in engagement with each other, but when the reed 5 swings outward it strikes the bushing 16 moving the spring 9 far enough tocause the associated cont-act to break away from the contact of the spring 8. These contacts then close again when the reed 5 swings in for the next stroke. The point at which the interrupter contacts open and close may be adjusted by the screw 14 which is provided with a lock-nut for holding it in its adjusted position. The unthreaded portion of the screw '14 passes through a hole in the spring 9 and its insulated tip rests against the spring 1 8 holdingthe latter at the desired point. The

spring 17 is provided to limit the forward movement of the pendulum bob 6 so as to limit the amplitude of the vibrations.

V The system-having been described generally, the detailed description of the operation of theapparatus will now be given. For this purpose it will be assumed that the subscriber at substation A, Fig. i, whose line terminates in Meadow, Figs. 1 and 2, desires to call the manual subscriber at substation A, Fig. 6,

whose line terminates inlrving, Figs. 1 and 3. When the receiver is removed at substation A, a circuit is closed over line conductors L01 and L02 for line relay 405 of the line switch LS. Line relay L05 thereupon energizes and places ground upon private normal conductor 103at armature 409, thereby making the calling line. busy to the connectors having 210-. ce'ss to it and closing a circuit through switching relay 104: and stepping magnet 411 in v series. At armature410 line relay .05 also connects test wiper 4:13 to the junction of switching relay 4:04 and stepping magnet 411. In case the trunk upon. which the wipers tl2-414 of the line switch LS are standing is. idle, this latter operation of line relay 105 is not of any particular utilityfand .switchingrelay 104i energizes, seizing the trunk.

' Assuming, however, that the trunk upon which the wipers of the line switch are standing is busy, switching relay 404- is short circuited bythe ground potential encountered by test wiper 113 and does not energize. Stepping magnet 411 energizes through the grounded test wiper 413 and operates the wipers 412%141, inclusive, step by step in,

search of an idle trunk by its buzzer-like action.

WVhen an idle trunk is reached, which trunk, it will be assumed, is the one comprisingfconductors 4e15417, inclusive, switching relay e04, being no longer-short circuited, encr gizes in series with stepping magnet 411;

opens the test circuit and prepares the holding circuit at arn'iatureklO'l; and at ari'naturcs 406 and 408 disconnects line conductors 401 and 402 from line relay 405 and ground and extends them by way of wipers c 12 and l-fl, conductors 415 and 417, and iii-matures 430 and 4:33 to the upper and. lower windings, l spectively, of the double wound relay 4-21 oi the trunk circuit TC. Line relay 421. now energizes over the calling line and closes a circuit for release relay 422 at armature 425. Release relay 422 new energizes in series with resistance 42% and places ground upon release trunk 4:16 at armature 4.26, thereby closing the usual holding circuit for swi 'ching relay of the line switch LS before the slow act ing relay 405 has had time to (lo energize.

In the trunk circuit TC, as a further resliilt of the energization of release relay 4-22, it prepares the operating circuit at armature s27; closes a circuit for switcl'ling relay and stepping magnet 4 20 of the director selector DS in series at armature 4-23; and at armature 4-29 connects the test wiper 443 of the director selector DS to the junction oi": sv-Jitching relay 435 and stepping magnet 440. Accordingly, the director selector D5 operates in the manner just described tor the line switch LS and selects an idle director. ii hen an idle director is selected, which. director it will be assumed is the one reached by way of cond 'ctors l li s-52, inclusive, switching relay energizes; opens the test circuit and grounds test wiper at armature e38 closes a further point in the og'ierating circuit at armature L39; and at ari'i'iatures 436 and 437 connects up wipers 4&1 and 142 thereby placing a closed loop .across conductors 414-5 and 44-3 of the selector S. This loop includes wipers 441 and. 442,, conductors it-l9 and 450, rest iug contactand armature 3&1, and the resting contact and. armature i and contacts 813 in multiple. Accordingly, li e relay 4-181 of the selector S energizes through the restin contacts and a matures 4:72 and 475, and closes a circuit for release relay 4:62 at armature {66. telease relay thereupon encrgizes, grounds release trunk conductor M7 at armature 4G7; and at armature 4:63 opens a point in the circuit of releaseinagnct M9 and prepares a circuit for vertical magnet 480.

In the seized director, release relay 806, Fig. 8 energizes through armature and its resting contact responsive to release trunk conductor in being grounded by the director selector DS, Fig. l, as above pointed out. Upon energizing, relay 806 connects up the timing lead 804; at armature prepares a locking circuit for relay 803 at armature 338; st armature 836 disconnects the bank of wiper of the counting switch. US from relay 805 and connects it to ground; disconnects release conductors 730 and 743 at armatures 83% and 835, respectively; opens the normal restoring circuit of the sender at armature 833; and at armature 837 closes a circuit for the interrupter 81 and relay 810 in series, thereby starting the interrupter to operate so as to have it running a steady rate when it comes into play. The pendulum 812 attracted when the above circuit is closed, but the marginal relay 810 not operatively energized on account of the high resistance of themugnet of the vibrating interrupter 811. Upon its inward swing the reed 312 engages a contact which short circuits the winding 811, where-- upon the reed swings outward. again and opens the contacts 313 upon the outward swin When the winding of the interrupte 811 is short circ itcd the ma 'inall y adj usted. relay SlO onees and ow ates armature 84-9 for a gnu-pose to be explz ned hereinafter. As pointed out hereinbeifore, a second point in the operating circuit was closed at armature 4.39, Fig. 4., upon the energization of switching relay oil the director selector DS. ll hen this occurs the vertical magnet of the oliice register Fig. 9,, is connected in multiple with the resistance through armature l-27 of relay 422 and its working contact, armature and its working contact, 1 ire-l4,conductor-452. rniature 850 and its conductor 733, series reley 'T( 2, conductor 739, resting; contact and armature Sir"), armature 923 and its resting contact, wiper 'Z'l?) of the sequence switch S and its first-contact, and conductor-741. Vertical ma..- i 909 is not energized over this circuit, however, on account oi" the high resistance of release relay 4-22 of the trunk circuit TC. 1

Vertical magnet 909 of the oilice register OR, Fig. 9, is connected to battery through the right hand winding of tlZS COIDlDOH dial tone transformer .r'tccordingly, the tone from the dial tone machine is transmitted back over the circuit just traced to the condenser 41%, Fig. 4, which is provided in order to enable the dial tone current to pass to the talking circuit through-the resting contact and armature to inform the calling subscriber that he may now dial the number.

In order to explain one ili'eature of the invention, it will be ass-ironed that the subscriber at substation it is called away from the telephone and does not replace his receiver. Ac-- cordingl nif special. provisions werenot made,

the director would remain tied up and an eX- pensive piece of equipment would be put out of service, so to speak, as regards handling calls for other subscribers. In order to pre vent this a timing arrangement has been provided which will cause the trunk circuit TC to be switched through and the director to be freed in case the first digit of the number is not dialled within a predetermined time. The circuits through which this timing apparatus functions are carried through the off-- normal contacts of thev ofiice register OR, Fi

9, so as to enable the director to be cut ott res contact, conductor 725, contacts 904:,

working contact, resting without transmitting any number in case the delay occurs before the first digit is dialled, and to enable a special number to be sent out in case a delay occurs betweenthe dialling of any two subsequent digits, as will be explained hereinafter. To continue with the description, it will be remembered that the common timing conductor 804, Fig. 8, was connected up at armature 439 upon the energization of release relay 806. upon the first closure of the contacts associated with the slow interrupter 803, ground is extended through armature 839 and its working contact, resting contact and armature 852, armature 847 and its resting contact, to the upper winding of the two-step V relay 808. -Relay 808 thereupon energizes part way only on account of the fact that its upper winding is composed oit a small nui'nbcr of turns of wire having a relatively high resistance. Accordingly, its first step armature 806 is operated but its second step armature 847 remains in its normal position. Upon being operated, armature 846 closes a locking circuit for relay 808 as follows: from ground by way of armature 706 of relay 702,

Fig. 7 and its resting contact, conductor 7 35,

conductor 860, armature 838 and its working contact, armature 846 and its working con tact, and the two windings of relay 808 in series. This locking circuit is not effective at this time, however, on account of the fact that the initial circuit is still established. A short time later the contacts of the interrupter 803 open again, opening the initial circuit of relay 808, whereupon the locking circuit through the two windings in series becomes effective, and the relay operates fully. Accordingly, armature 847 opens a further Joint: in the initial circuito'l' the upper winding or? the relay and prepares a circuit for switching relay 814. After an interval of say one minute the slow interrupter 808 closes its associated contacts again, thereby com- Dieting a circuit through armature 839 and contact and armature 852, armature 847 and its working contact, normally closed contacts controlled by armature 845, conductor 862, oil normal spring 907 and its resting contact of the office register OR, Fig. 9, switching conductor 731,

. normally closed contacts controlled by armature 85-3, and switching relay 814 to battery. Switching relay 814 now energizes and locks to the grounded release trunk conductor 451 and opens its initial circuit at armature and at armature 850 disconnects the combined switching and operating conductor 452 from cond ctcr 725 and connects it to ground, thereby completing a circuit over conductor 452 and through wiper 444 of the director selector DS, working contact and armature 439, working contact and armature 427, and the normally open contacts controlled by armature 425 for the switching re- 7 Accordingly,

lay 423 of the trunk circuit TC. Switching relay 423 now the grounded release trunk conductor 447 at armature 453; connects release trunk conductor' 416 to the release trunk conductor 447 at armature 432'; removes battery from vertical magnet 480 of the selector S at armature- 431; and at armatures 430 and 433 disconnects conductors 415 and 417 from line relay 421 and connects them instead to conductors 445 and 448 of the selector S, at the same time disconnecting the latter from the control loop of the director. Line relay 461 of the selector S is now maintained energized over the calling line, but the vertical magnet 480 cannot be operated in case the calling subscriber returns to the phone and manipulates his calling device, because battery is removed from the vertical magnet 480 at armature43l.

Responsive to being disconnected, line relay 421 of the trunk circuit TC falls back and short circuits the associated release relay 422 which, accordingly, deenergizes after a slight interval and opens the circuit of switching relay 435 of the director selector DS at armature 428, whereupon relay 435 deenergizes, freeing the director.

It will now be assumed that the calling subscriber is not called away from his telephone] and that he hears the dial tone impressed upon his line through the vertical magnet of the office register OR, Fig. 9, in the hereinbefore described manner, and dials the first-digit 6 in the desired number. Accordingly, when the calling device is oper ated six interruptions are produced in the circuit of line relay 421. of the trunk circuit TC, which line relay is accordingly deenergizedsix times momentarily. Upon each decnergization of line relay 421 the switching relay 423'is disconnected to prevent it :l'rom being operated at this time, and release relay 422 is short circuited at the contacts controlled by armature 425. Release relay 422 does not deenergize during this operation owing to the fact that it is short circuited and its circuit is not opened, making it slow acting as is well known. Each time release relay 422 is short circuited a ground potential is extended through armature 427 and its working contact, armature 439 and its working contact, and wiper 444 to the operating conductor 452, thereby closing a circuit over the previously traced path to vertical magnet 909 of the oliice register OR, Fig. 9, through wiper 719 otthe sequence switch S, Fig. 7. Accordingly, vertical magnet 909 is energized six times momentarily and, upon each energization, raises the wipers 941 944, inclusive, one step, resulting in the said wipers being raised opposite the sixth level of bank contacts.

Upon the first upward step of the wipers of the office register, the oil normal contacts 906 are closed, connecting the spark condenser energizes and locks itself to 908 to conductor 733 which is connected to the impulse distributing wiper 719 of the sequence switch S,- through series relay 702 and armatures 916 and 923. .Accordingly, the spark which would otherwise be produced upon the opening of the circuit of vertical magnet 909 and series relay 702 is quenched by the condenser 908. It may be pointed out that this condenser not normally connected to the operating circuit because if it ere the dial tone impressed upon the operating circuit through vertical magnet 909 would be practically short circuited by the fairly heavy condenser 908.

Relay 782 is energizeiil in series with vertical magnet 909 upon the first impulse oi? current delivered to the latter, and, being slow acting, maintains its armature attracted throughout the vertical movement. Upon energizing, relay 702 closes at armature 706 a circuit for the slow acting relay 701 which thereupon. energizes and prepares at armaturc .705a circuit for the operating 717 of the sequence switch 9. Accordingly, when series relay 702 deenergizes at the end of the first series of impulses, it closes at armature 706 a circuit for magnet 717-t-hrough the working contact and armature 705 whereupon r agnet 717 energizes and advances the wipers 718 and 719 one step, and wiper 719 shifts the operating circuit from the vertical magnet of the oiiice register to the rotary magnet. Relay 702 also opensthe circuit of the slow acting relay 701 which deenergizes an instant later, opening the circuit of magnet 717 at armature 705.

When the callin v subscriber dials the second digit 0 in the desirednumber, ten impuls .s of current are sent to the director over the operating circuit to the impulse distrih uting wipers 719 of the sequence switch 53 and then overconductor 7412 to the rotary magnet 910 of the oilice register OR, ily the operation ot the rotary magnet 910 the wipers of the oiiice register GR are rotated step by stop until they come into engagement with the tenth set oi? bank contacts in the '11 level, which is the set of contacts shown in the drawings. Series relay 702 is energized over the operating circuit a before and, together with the associated slow acting relay 701, causes the advance of the sequence switch S at the end of the series of impulses in the hereinbefore dcscrihed manner.

Responsive to the dialling (it the third digit 1 in the desired number, one impulse of current is delivered over the operating circuit to wiper 719 of the sequence switch 5 and is then transmitted through series relay 712 and conductor 751 to thestepping magi'ret 100 1- of the digit register DB Fig-19 which thereupon energizes and advances the wiper 1005 into engagement with the ii a ted bank contact.

The wipers 719 and 718 of the sequence switch S are again advanced one step in the usual manner, and wiper 719 connects the operating circuit through conductor 7 52 to the stepping magnet of the second digit register DB Fig. 10. However, the automatic subscribers are instructed not to dial the last three digits in the manual numbers and to wait until the operator answes and then give her the complete desired number. Accordingly, the subscriber at substation It does not dial any further digits at this time.

Returning now to the point which the wipers 718 and 719 of the sequence switch S were advanced into engagement with the third set of associated bank contacts at the en d of the rotary movementof the office register OR, the operation of the oitice register OR has been compl "ed at this time and the sender may now be d. Accordingly, wiper 718 of the sequence switch 55, upon coming into engagement with its third associated bank contact, places ground upon the start conductor control wiper oi the sequence switch S, wiper 718 being grounded over conductor 727 and through the resting contact and armature 8 10 of relay 807, Fig. 8.

Responsive to the ground potential being placed upon wiper 722,51 circuit is closed through the contact in the bani; o1 wiper 722 and through the resti 11g contacts and armature 708 and start conductor 788 for the stepping magnet 817 017 the counting switch CS, Fig. 8, by way 015 the resting contact and armature 84:9 of the marginal relay 810, and armature 851 and 859. Upont ie next deenergization of stepping relay 810, a circuit is closed at armature 8 19 for the stepping magnet 817 ot the counting switch Stepping magnet- 817 thereupon energizes and advances the associated. pawl into engagement with the next notch in the wiper driving ratchet wheel but does not move the wipers 819 and 820. Upon the tollowirq euergization of stepping relay 810 the circuit f stepping magnet 817 is again opened whereupon the said magnet 817 ('lcenergizes and l the wipers 819 advances and 820 one step in a counter clockwise direction, whereupon pickup relay 815, which is con. ate to the pick-up wiper 819, energizes through the first grounded contact in the picleup bank and armature 838 and its.

working contact; prepares a. locking circuit tor stop relay 816 at armature 855; and at armature 85 1 removes the shunt from i'()ll'1tl the sending contacts 813 of the vibrator 811. This occurs at about the time the pendulum 812 is in its extreme left position and the contacts are closed.

V7 hen the pendulum 812 subsequently swings to the right, it removes the shunt from around the w nding 811 and permits relay 810 to tie-energize and close the circuit of stepping magnet 817 again at armature 8 19, ant

at armature contacts 813 the pendulum 812 Cir step relay 816, initially,

working opens the outgoing control circuit. At the end ct this interruptlon 1n the control circuit the 0011 811 is again short circuited and the relay 8 10 again energizes to open the circuit of the stepping magnet 817, whereupon the said stepping magnet 817 again deenergizes and the wipers 819 and 820 are advanced another step. Wiper 820, accordingly, engages a contact in which the first impulse stop conductor terminates. However, since this conductoris not grounded at this time the stop relay 816 is not energized. This operation continues as described under the control oi the interrupter 811 and the wipers 819 and 820 continue to be advanced one step after each opening" in the outgoing control circuit with the bank contact in which the third impulse stop conductor 953 terminates, thereby closing a circuit for stop relay 816 as follows: From ground by Way 01" the grounded stop conductor control wiper 724:, the first associated hank contact, stop conductor7 61, wiper 941 of the oftice register OR, hank contact 961, jumper971 on the intermediate distributing irame 1B1, the third impulse stop conductor 953, the corresponding contact in the bank of wiper 820, wiper 820, and stop relay 816110 battery. Stop relay 816 now energizes over this circuit and closes a locking circuitfor itself at armature 858; disconnects stepping magnet 817 at armature 859; shunts the impulse contacts 813 at armature 856; and at armature 857 closes the automatic :oring circuit tor the counting switch CS.

it will be noted that the stepping magnet 720 of the sequence multiple with sto conductor 726. viously mentioned closure of the circuit of a circuit is closed for stepping magnet- 720 which accordingly energizes in preparation for the advance of the wipers 7522, 723 and 72 1.

The counting switch CS is new advanced to its normal position by the buzzer-like action of the sell-interrupting stepping magnet 817, which operates through the interrupter contacts 818, armature 857 and its working contact, wiper 819, the associated bank of contacts and armature 836 and its contact. The restoring circuit is broken and the circuit of pick-up relay 815 is opened when Wiper grounded bank cont-act.

Pick-up relay 815,

vdeenergizes responsive to switch S is connected in relay 816, Fig. 8, through accordingly,- upon the pro-' day 4164 and rotary magnet 4:76 continues 819 passes off the last i however, does not deenergize right away he cause it is slow acting.

In the selector S, Fig. 4, line relay 461 each of the three interruptions produced in the outgoing control circuit in thedirector, and upon each deenergization completes at armature 4166 a circuit through armature 4:68 and its working contact and series relay 41-63 for vertical magnet 4181). By the operation of vertical magnet flSO the wipers 182&84, inclusive, are raised step by step and come to rest opposite the third level of bank contacts, Relay e163 isenergized in series with vertical magnet 480 and, being slowacting, maintains its arm ature attracted throughout the vertical movement Upon energizing, relay468closes at armaturedGE) a circuit for stepping relay 164: through the oil normal contacts 181 which close upon the first vertical step and the interrupter contact 477. Upon energizing, steppingrelay 4:6 1 closes a locking circuit for itselfv at armature470, and at armature 171 pre JQTGS a circuit for rotary magnet 476.

At the end of the vertical movement slow acting series relay e63 falls back and com pletes at armature 469 the circuit of rotary magnet 176 which thereupon energizes and advances the wipers 182 1%, inclusive, into engagement with the first set of contacts in the third. level and, near the end of its stroke, opens the circuit of stepping relay 4.164: at

contacts 4-7 7 Stepping relay 4:64: now deenergizes and opens the circuit of rotary mag ct 1(1) at armaturej4l71, whereupon rotary magnet 4:46 deenergizes also and closes its inter- V ruptcr contacts 477 again.

In case the trunk terminating in the first set of bank contacts is idle, switchii relay 165 energizes seizing the trunk. Assuming, however, that the trunk is busy, switching relay 165 is short circuited by the ground potential encountered upon the busy test contact by test wiper 183 and does not energize, and stepping relay 46 1 c ergizes through test Wiper and closes a circuit for rotary man} net 176 at armature 1 1, whereupon rotary magnet 176 energizes again advancing the wipers into engagement with the next set of haul: contacts. 1 7. v

This alternate operation stepping re- 7 (ii clesci1l: e(l. until an idletrunl; is reached, which trunk it will be assumed is the one comprising conductors l187, inclusive. I 7 is reached, switching relay 165, being no longer short c1rcu1ted, en-

lVhen this idle trunk ergizes in series with stepping relay 46a, hut stepping relay 164; does not energize at this time on account of th high resistance of switching relay 465. Upon energizing,

switching relay 165 opens the test circuit and prepares the holdingcircuit at armature e78; removes ground from arn'iature 466 or line relay 161 at armature e7 1,therebyopenmg the circuit of the slow acting release relay 462; and at armatures 4:72 and 475 disconnects conductors 44:5 and 448 from line relay 461 and extends them by way of wipers 482 and 484C and conductors 4185 and $87 to the upper and lower windings of the double wound line relay 501 of the repeater R through the upper and lower left hand windings of the associated repeating coil. Relay 501 now energizes over the outgoing control circuit of the director and closes at armature 503 a circuit for release relay 502 which thereupon energizes and places ground upon release trunk conductor 486 at armature 5053, thereby closing the usual holding circuit for switching relay d5?) of the selector S before the slow acting release relay has had time to deenergize.

In the repeater ll, as a further result of the energization of line relay 501, it closes a bridge across the associated inter-office conductors leading to the selector 8" in Cedar at armature 504:, whereupon the selector 5% is prepared for operation in the usual manner. In the director, the slow acting); pick-up relay 815, Fig. 8, deenergizes after the interval tor which it is adjusted and opens the circuit of stop relay 816 and of stepping magnet 720 of the sequence switch S, F 7, at armature 855, and at armature 854: places another out around the sending contacts 813. Steppl magnet 720 now deenergizes and advanc-i the sequence switch wipers 722 134, inclusive. into engagement with the second of bani: contacts, and stop conductor control wiper 724: removes ground from the first code digit stop conductor 761 and places ground on the second code digit stop conductor 762 preparatory to the transn'iission of the second digit in the desired number. This later operation does not have any particular ut it at this moment for the reason that the second digit, being 0, does not require a jumper to be run on the .intern'iediate distributing frame lllJF. According y, the bank contact 902 with which the second wiper of the otlice register is new in r ,aggement is not connected up on the intern..edi.ate distributing frame.

After the interval for which it is adjusted the slow acting stop relay 81-5 of the sender also deenergizes and again connect-s up the stepping magnet 817 to the start circuit at armature 859, thereby initiatin the transmission of the second (I t 0. .[is pointed out above, none of the impulse stop conductors are grounded at this time, and the counting switch S continues to advance and the stop relay 816 is not energized until the last contact in the bank of wiper 820 is reached, which contact is grounded locally. The stop relay 816 then energizes with the result that the digit being transmitted is terminated in the same manner as pointed out in connection with the nrst code digit 3.

Responsive to the transmission of the second code digit 0 the line relay 501 of the repeater R, F 5, deenergizes ten times momentarily and, upon each deenergization, opens the bridge across the associated inter-ofiioe trunk conductors at armature 504, with the result that the selector S in Cedar is operated in the well known manner to raise its wipers opposite the tenth level of bank contacts and select an idle trunk, which trunk, it will be assumed, is the one extending to the repeater R". Accordingly, the repeater R operates in the same manner as the repeater 1t and prepares the distant selector S in Edgewater for operation in the usual manner.

In the director, the sequence switch S is advanced another step in the hereinbetore described manner, and wiper 72 i grounds the third code digit stop conductor T63 preparatory to terminating the third code digit 6.

The sending operation is again started in the usual manner and continues until stop relay 816 is energized at the end of the sixth interruption or" the outgoing control circuit. The circuit of stop relay 816 at this time is as follows: From ground by way of the groundeo stop conductor control wiper 79A of the sequence switch S, the third associated bank contact, the third code digit stop conductor 763, the third wiper 948 of the oi'iice register Olt, bank contact 963, jumper 972 on the intermediate distributing frame IDF, the sixth impulse stop conductor 956, the cone spending contact in the bank 01"? wiper 820 of the counting switch'CS, wiper 820, and stop relay 816 to battery.

In the othce Edgewater, the selector S raises its wipers opposite the sixth level responsive to the transmission of the third code digit 6 and selects an idletrunlr, which trunk, it will be assumed, is the one extending to the repeater R Accordingly, the repeater ll operates in the same manner as described for the repeater R and auses the distant selector in Main to be prepared for operation in the usual manner.

The sequnce switch S oi the director is again advanced after the third digit and wiper 72 i grounds the fourth code digit stop conductor 76%. l Vhcn thi occurs, relay 901, Fig. 9, energizes over conductor 764. and through wiper 9 H ot the office register OR, hank contact 961%, juniper 9'73, and the normally closed co ts controlled by armature Upon en ng, relay 901 closes a locking circuh 1 self ant opens its inral circuitat armature 914i, and at armature 915 connects the umper 973 to another terminal on the intermediate distributing frame so that in case the digit to be transmitted is anything other than 0 a conductor can be run to the correct impulse stop conductor to terminate such digit. As a further result of the cue ization of relay 901, the second subsciihei Cllglt SLOP conductor H2 is dlsconnected from the associated conductor 772 and is connected instead to the switching conductor 781 so as to cause the switching relay to be operated when the sequence switch S is advanced after one subscriber digit has been transmitted. It will be understood, of course, that the term code digit is used herein to indicate any digit transmitted under the control of the office register OR, and that the term subscriber digit is used toindicate any digit registered upon and subsequently retransmitted under the control of one of the digit registers DR -DRZ inclusive.

The fourth code digit being 0 does not require any jumper on the intermediate distributing frame IDF and is terminated in the usual manner when the stop wiper 820 of the counting switch CS engages its last bank contacts.

Responsive to the transmission of the fourth code digit 0, the selector S in Main raises its wipers opposite the tenth level of bank contacts and selects an idle trunk, which trunk, it will be assumed is the one extending to the selector S That beingthe case, the selector 8 is prepared for operation in the usual manner.

in the director, the sequence switch S is advanced in the usual manner after the transmission of the fourth code digit 0, and the stop conductor control wiper 724E grounds the first subscriber digit stop conductor 771 preparatory to the termination of the first subscriber digit. Wiper 722 at this time moves out of engagement with its fourth contact and into engagement with its fifth contact, thereby opening the circuit through which ground was initially supplied to the starting conductor 78S and placing ground on start conductor 738 through a new path which includes the resting contact and armature 713 of the slow acting series relay 712, conductor 743 and off normal contacts 1.001 of the digit register DR. This circuit is taken through the contacts of the slow acting relay 712 and through the oli normal contacts 1001 to insure that the sender is not started to transmit the first subscriber digit before such digit is completely registered. How

ever, assuming that the first subscriber digit- 1 in the desired numberis registered before the last code digit is transmitted, there is no break in the start circuit following the transmission of the last code digit and the sender is again started after the usual interval occasioned by the slow acting relays 815 and 810.

It will be remembered that the digit registor DR responded to the digit: 1. Accordl ingly, this digit 1 is now retransmitted and t the end of one interruption in the outgoing control circuit the wiper 820 of the counting switch CS finds ground on the third associated bank contact, thereby closing the following circuit for ground by way 01 the stop conductor constop relay 816: From' trol wiper 7 24 of the sequence switch S, the first subscriber digit stop conductor 771, wiper 1005 of the digit register DB the first associated bank contact, the first impulse stop conductor 951, the corresponding contact in the bank of wiper 820, wiper 820, and stop relay 816 to battery. This energization of stop relay 816 results in the digit 1 being terminated in the hereinbefore described manner.

Responsive to the transmission of the digit 1, the selector S in Main, Fig. 5, raises its wipers opposite the first level and selects an idle trunk, which trunk, it will be assumed, is the one extending to the repeater R Accordingly, the repeater R operates in the same manner described for the repeater R, with the result that abridge is closed across the associatedv inter-ofi'ice trunk conductors 601 and 602. Responsive to the closure of this bridge, line relay 603 of the cord circuit CC energizes and closes at armature 604 a circuit througl'i armature 608 and its resting contact, and the resting contact and armature 610 for the lamp 611 which, accordingly, becomes lighted to inform the operator that a call has come in over the associated trunk line.

In the director, the wipers of the sequence switch S are again advanced in the usual manner subsequent to the termination ofthe digit 1, and wiper 724 places ground upon the second subscriber digit stop conductor 772 preparatory to terminating the second subscriber digit in case one is registered.

At this time, however, the registered number contains only one subscriber digit and relay 901 is energized as hereinbefore pointed out. Accordingly, the placing of ground upon conductor 77 2 results in a circuit being closed for switching relay 815 as follows: From ground by way of the grounded wiper 7 24: of the sequence switch S, conductor 772, armature 913 of relay 901 and its working contact, switching conductor 781, normally closed contacts controlled by armature 853, and switching relay 814 to battery. Switching relay 8141, upon energizing, closes a lockinig circuit for itself and opens its initial circuit at armature 853; disconnects the timing conductor 804*. from relay 808 at armature 852; opens the starting circuit at armature 851; and at armature 850 disconnects the combined switching and operating conductor 4152 from the operating conductor 7 25 and connects it to ground, resulting in the energization of switching relay 423 or the trunk circuit TC over the hereinbefore traced oath. Accordingly, switching relay 423 switches the connection through and cuts off the line relay 4:21, whereupon the line relay oi the repeater B, Fig. 5, is maintained energized under the direct control of the calling line, The release relay 41-22 of the trunk circuit TC deenergizes after an interval and opens the circuit of switching relay 4350f the 

